NURS 2004 Pharmacology: Medication Therapy for the Gastrointestinal

what are 3 main types of drugs affecting the GI system

1. antiemetic and antinausea agents

2. antidiarrheals and laxatives

3. acid controlling agents

what is nausea defined as

the sensation that leads to the urge to vomit

what is vomiting or emesis

the forcible emptying of gastric contents or intestinal contents

what do the sensations of nausea protect us from

ingesting toxic substances by expelling them from our body

how do we vomit from an irritating toxin

an irritating toxin will stimulate receptors in the GI tract which sends signals to the brain that causes us to vomit

what are the 2 main centers in the brain that cause nausea and vomiting

1. chemoreceptor trigger zone

2. vomiting center

what is the chemoreceptor trigger zone triggered by

drugs or toxins

what 9 things is the vomiting center triggered by

1. odors

2. smells

3. tastes

4. sights

5. motion

6. surgery

7. states of shock

8. infections

9. middle ear disturbances triggered from vestibular center

what is a nausea more difficult to treat

nausea and vomiting related to chemotherapy

there is usually an underlying __________ for nausea and vomiting

cause

why may you sometimes not want to treat nausea and vomiting

you want to expel toxins

what is the first line of treatment for nausea and vomiting

try ginger ail, rest, cold cloths, ginger, peppermint, dry crackers first. not drugs

can antiemetics and anti-nausea drugs be used in combination

yes

how do both antiemetics and anti-nausea drugs work

they work by blocking a different pathway to the vomiting center, thereby blocking the stimulus that is inducing vomiting

how are antiemetics available

by prescription or OTC

when antiemetics are OTC what will they treat

very mild nausea and vomiting

what three areas can trigger the chemoreceptor trigger zone

1. gastrointestinal tract

2. labyrinth (inner ear)

3. cerebral cortex

what part of the brain is the vomiting center located in

the medulla

what do anticholinergic drugs block

they block acetylcholine receptors in the vestibular nuclei and the reticular formation

what do anticholinergic drugs prevent

they prevent nauseous stimuli from being transmitted from the ear to the chemoreceptor trigger zone

what do anticholinergic drugs dry

they dry GI secretions and reduce muscle spasms

what three things would indicate the use of an anticholinergic drug

1. dry mouth

2. drowsiness

3. secretion reduction before surgery

what are 3 adverse events from anticholinergic drugs

1. dry mouth

2. drowsiness

3. constipation

what is the contraindication for anticholinergic drugs

having narrow-angle glaucoma (causes pupillary dilation)

what is the prototype anticholinergic drug

scopolamine

anticholinergic drugs are blockers, or __________________

antagonists

what are transderm V anticholinergic patches used for

they are placed behind the ear to prevent motion sickness, and used in palliative clients to clear the death rattle sound

what do antihistamine drugs bind to and block

histamine (H1) receptors

what do antihistamine drugs prevent

cholinergic stimulation in the vestibular and reticular systems

what do antihistamine drugs inhibit

acetylcholine

what other 2 effects do antihistamine drugs have

1. antisecretory effects

2. antispasmodic effects

what are the 2 indications to use antihistamine drugs

1. motion sickness

2. nausea and vomiting

what is the adverse event of antihistamine drugs

anticholinergic effects because they block the actions of acetylcholine

what is the main example and prototype of antihistamine drugs

dimenhydrinate, or gravol

what do antidopaminergic drugs block

dopamine receptors in the CTZ

what properties may antidopaminergic drugs have

they may have anticholinergic properties, blocking acetylcholine and calm the CNS

what is the indication to use antidopaminergic drugs

nausea and vomiting

what are the 4 adverse events of antidopaminergic drugs

1. tachycardia

2. pseudo-parkinsinism

3. extra-pyramidal symptoms

4. bradykinesia

what is pseudo-parkinsonism

this is tremors, muscle rigidity, and jerky movements

what could extra-pyramidal symptoms be

dystonia, or a lack of muscle tone

what are antidopaminergic drugs mostly used as

antipsychotics, but can also be used as antiemetics because they do block dopamine and receptors in the CTZ

when will you use antidopaminergic drugs

when gravol is not working, as they are only available by prescription

why do you get pseudo-parkinsonism symptoms with antidopaminergic drugs

because they block dopamine

what do prokinetic drugs block

dopamine receptors in the CTZ, desensitizing the CTZ

what do prokinetic drugs stimulate

acetylcholine receptors in the GI tract, increasing peristalsis

what are the 4 indications to use prokinetic drugs

1. delayed gastric emptying

2. gastroesophageal reflux

3. cancer therapy

4. post-op nausea and vomiting

what are the 2 adverse effects of prokinetic drugs

1. extrapyramidal effects

2. tardive dyskinesia (with long term use)

why are extrapyramidal effects seen with prokinetic drugs

since they block dopamine

what is tardive dyskinesia

an uncontrollable movement of the tongue

what is the contraindication for prokinetic drugs

a GI obstruction, like a blockage in the bowel

what is the prototype prokinetic drug

metoclopramide (shouldn't be on it long term)

what do serotonin blockers block

they block 5-HT3 serotonin receptors that are located in the GI tract, CTZ, and vomiting centre

what are the 2 indications for using serotonin blockers

1. cancer therapy

2. post-op nausea and vomiting

will serotonin blockers affect serotonin in the synapses

no

why are there no adverse effects worth talking about with serotonin blockers

because they have such a specific job

tetrahydrocannabinoid agents (THCs) have an _____________ effect

inhibitor

where do THCs send their inhibitor effect

certain areas of the brain (3):

1. reticular formation

2. thalamus

3. cerebral cortex

what do THCs alter

mood and the body's perception of its surroundings, this helps with N & V

what are the 2 indications to use tetrahydrocannabinoid agents

1. cancer therapy

2. anorexia associated with weight loss in clients with HIV or cancer

why should antiemetics not be taken with alcohol

they can cause drowsiness

why should antiemetics not be taken with other CNS depressants

they will get anticholinergic or antihistamine effects

what is a herbal product commonly used for nausea and vomiting

ginger

what may ginger increase

the absorption of all oral medications

why should you not take ginger with anticoagulants and antiplatelets

it increases the bleeding risk

slide 17: which antiemetic drugs can the nurse expect to prepare that are known to cause drowsiness and a drying of secretions? (3)

1. antihistamines

2. antidopaminergic drugs

3. anticholinergics

antidiarrheal agents are used to treat stools that have... (3)

1. increased frequency

2. increased liquidity

3. increased weight

what does diarrhea cause a loss of

fluid and electrolytes

diarrhea is a ______________

symptom

what are 7 reasons why someone may have diarrhea

1. contaminated food

2. fecal impaction

3. bacteria or viruses

4. toxins

5. drug reactions

6. laxative abuse

7. malabsorption syndrome

what is the best action when it comes to treatment of diarrhea

prevention

in goals of diarrhea treatment, we want to decrease what

stool frequency

in goals of diarrhea treatment, we want to alleviate what

abdominal cramps

in goals of diarrhea treatment, we want to replenish

fluids and electrolytes

in goals of diarrhea treatment, we want to prevent what

weight loss and nutritional deficits from malabsorption

why may people have to be on supplemental vitamins with malabsorption

because they lose a lot

when should antidiarrheals not be used

when trying to get rid of bacteria and parasitic worms

what do adsorbents coat

the walls of the GI tract

what do adsorbents bind to

the causative bacteria or toxin, and then it is eliminated through the stool

adsorbents can cause ____________ bleeding time

increased

can adsorbents cause constipation

yes

adsorbents can cause __________ stools

dark

what 3 other things can adsorbents cause

1. confusion, twitching

2. hearing loss, tinnitus, metallic taste

3. black tongue

what are the interactions of adsorbents

many! affects absorption in the GI tract

when will active charcoal be used

when someone overdoses

anticholinergics _______ peristalsis

slow

how do anticholinergics slow peristalsis

by reducing the rhythmic contraction and smooth muscle tone of the GI tract

anticholinergics have a _____________ effect

drying

anticholinergics cause urinary ______________

retention

anticholinergics cause _________________ in males

impotence

what 6 other things can anticholinergics cause

1. headache

2. dizziness

3. confusion

4. anxiety

5. drowsiness

6. dry skin

what do opiates and opiate related agents decrease

bowel motility

what do opiates and opiate related agents increase

transit time

what do opiates and opiate related agents relieve

rectal spasms

what do opiates and opiate related agents help with pain relief from

diarrhea

what is the indication to use opiates

only used in situations of severe diarrhea

what are 5 adverse events of opiates and opiate related agents

1. drowsiness

2. sedation

3. dizziness

4. lethargy

5. respiratory depression

opiates are _______ depressants

CNS

what are the 2 components of opiate lomotil

1. diphenoxylate

2. atropine

probiotics are generally referred to as what

good bacteria

what do probiotics suppress the growth of

they suppress the growth of diarrhea-causing bacteria and re-establish the normal flora